using System;

using System.Linq;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var data = new []{

        new { line = 1, ship="jonata", altro="baba"},

        new { line = 1, ship="glauco", altro="baba"},

        new { line = 2, ship="jonata", altro="baba"},

        new { line = 2, ship="glauco", altro="baba"},

        };

        var aggregate = data.GroupBy(d => new {d.line, d.altro})

            .Select(g=>new { 

                line = g.Key.line, 

                altro = g.Key.altro, 

                ship = string.Join(", ", g.Select(g2 => g2.ship))})

            .ToList();

        var json = JsonConvert.SerializeObject(aggregate);

        Console.WriteLine(json);

    }

}